Margin Space between div and header is undesired white

Question

The margin space between div1 and header is undesired white, even though I declared the background as grey (rgb:243,243,243). I want to get rid of the white space between div1 and header.

I tried different ways to fix that like changing the colours or adjust the margin and padding but nothing worked.

.header {
  width: 100%;
  height: 8.5vh;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 20px;
  background-color: rgb(243, 243, 243);
  z-index: 1000;
}

.header-fixed {
  position: fixed;
}

.shadow {
  box-shadow: 0px 0px 8px rgba(0, 0, 0, .6);
}

.header .logo {
  margin-left: 2vh;
  font-size: 1.5em;
  text-decoration: none;
  color: black;
}

.header ul {
  margin-left: 2vh;
  margin: 0;
  padding: 0;
  list-style: none;
}

.header li {
  margin-right: 20px;
}

.header li:last-child {
  margin-right: 0;
}

.header li a {
  text-decoration: none;
  color: black;
  padding: 10px;
  border-radius: 5px;
}

.header li a:hover {
  background-color: #f4f4f4;
}

.header .logo {
  font-size: 2em;
  text-decoration: none;
  color: black;
}


/* menu */

.header .menu {
  top: 0;
  position: sticky;
  width: auto;
  clear: both;
  max-height: 0;
  transition: max-height 0.2s ease-out;
  margin-right: 3vh;
}


/* menu icon */

.header .menu-icon {
  cursor: pointer;
  display: inline-block;
  position: absolute;
  /* Geändert von 'float: right;' zu 'position: absolute;' */
  right: 0;
  /* Hinzugefügt, um das Icon rechts auszurichten */
  padding: 28px;
  padding-left: 5%;
  -webkit-user-select: none;
  user-select: none;
  z-index: 1000;
  /* Stellen Sie sicher, dass das Menü über anderen Elementen liegt */
}

.header .menu-icon .navicon {
  background: #333;
  display: block;
  height: 2px;
  position: relative;
  transition: background 0.2s ease-out;
  width: 18px;
}

.header .menu-icon .navicon:before,
.header .menu-icon .navicon:after {
  background: #333;
  content: "";
  display: block;
  height: 100%;
  position: absolute;
  transition: all 0.2s ease-out;
  width: 100%;
}

.header .menu-icon .navicon:before {
  top: 5px;
}

.header .menu-icon .navicon:after {
  top: -5px;
}


/* menu btn */

.header .menu-btn {
  display: none;
}

.header .menu-btn:checked~.menu {
  max-height: 240px;
}

.header .menu-btn:checked~.menu-icon .navicon {
  background: transparent;
}

.header .menu-btn:checked~.menu-icon .navicon:before {
  transform: rotate(-45deg);
}

.header .menu-btn:checked~.menu-icon .navicon:after {
  transform: rotate(45deg);
}

.header .menu-btn:checked~.menu-icon:not(.steps) .navicon:before,
.header .menu-btn:checked~.menu-icon:not(.steps) .navicon:after {
  top: 0;
  .div1 {
    margin-top: 5vh;
    margin-bottom: 2.5vh;
    display: flex;
    background-color: rgb(243, 243, 243);
    flex-wrap: wrap;
    gap: 2%;
    /* Vertikaler und horizontaler Abstand zwischen den Elementen */
    justify-content: space-between;
    /* Sorgt für gleichmäßigen Abstand zwischen den Elementen und zum Rand */
    height: 100vh;
    padding-left: 2%;
    padding-right: 2%;
  }
  .picture-container {
    display: flex;
    flex-direction: column;
    margin-top: 0;
    margin-bottom: 3vh;
    flex: 1;
    min-width: calc(50% - 2%);
    height: 80%;
    overflow: hidden;
    /* Verhindert das "Auslaufen" von inneren Inhalten außerhalb der abgerundeten Ecken */
  }
  .img-container {
    flex-grow: 1;
    overflow: hidden;
    /* Diese Zeile hinzugefügt */
    background-color: #fff;
    /* Hintergrundfarbe, passend zu Ihren Bildern oder der Website */
  }
  .img-container img {
    object-fit: cover;
    width: 100%;
    height: 100%;
    transition: transform 0.8s ease-in-out;
  }
  .footer {
    background-color: white;
    flex-shrink: 0;
    /* Verhindert, dass der Footer schrumpft */
    height: 13%;
    /* Höhe des Footers, anpassbar nach Bedarf */
    display: flex;
    /* Erlaubt die Zentrierung von Inhalten im Footer */
    align-items: center;
    /* Zentriert den Inhalt vertikal */
  }
  .footer h3 {
    font-size: 24px;
    /* Größere Schriftgröße */
    color: #000;
    /* Stellt sicher, dass die Schriftfarbe kontrastreich genug ist */
    padding: 20px;
    /* Etwas Platz um den Text */
    margin: 0;
    /* Entfernt jeglichen Standardabstand */
    font-weight: 300;
    font-size: 30px;
    /* Überschreibt vorherige Schriftgröße */
    letter-spacing: 0.06em;
    line-height: 50px;
  }
}

<header class="header">
  <a href="" class="logo">COMPANY</a>
  <input class="menu-btn" type="checkbox" id="menu-btn" />
  <label class="menu-icon" for="menu-btn"><span class="navicon"></span
        ></label>
  <ul class="menu">
    <li><a href="#about">ABOUT</a></li>
    <li><a href="#contact">A</a></li>
    <li><a href="#careers">B</a></li>
  </ul>
</header>
<div class="div1">
  <div class="picture-container">
    <div class="img-container">
      <img alt="Bild ist nicht verfügbar" src="https://allgemeinebauzeitung.de/media/_processed_/c/5/csm_peri-geruestbau-geruestbautechnik-naechste-generation-im-geruestbau-vereint-vorteile-von-rahmen-und-modul-45646-1_acfa19c3af.jpg" />
    </div>
    <div class="footer">
      <h3>GERÜSTBAU</h3>
    </div>
  </div>

  <div id="picture-container2" class="picture-container">
    <div class="img-container">
      <img alt="Bild ist nicht verfügbar" src="https://www.betriebsratspraxis24.de/wp-content/uploads/sites/52/2023/01/AdobeStock_283383067-1024x683.jpeg" />
    </div>
    <div class="footer">
      <h3>BAU</h3>
    </div>
  </div>
</div>

Answer 1

You could add a background color to the body:

body {
  background-color: rgb(243,243,243);
}

This will make your whole page a certain color.